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Engine Ticking Noise


TPIGroove

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I see the plug wires are marked to match the numbers on the terminals but are the wires actually connected in that order? I cannot imagine that they are or only two cylinders would be connected correctly, although it has been proven that the 3800 can run on only two cylinders 180degrees apart. The basic wire routing looks about right, the left side in the photo are the odd numbered cylinders and I can see they are entering the wire loom on the front valve cover which is normal. The even numbered cylinders go to the rear of the engine and that appears to be correct but the numbering and actual cylinder locations are very clearly mismatched. The best thing to do would be to take the coil pack off the ICM and reverse it so the numbering is correct. Strictly speaking, that doesn't need to be done but at the least, I would reverify the spark plug wires are connected to the correct cylinder and they connect to the correct terminal as shown in the diagram above. Reversing two wires at the rear of the engine is a common problem that has caused even the best of us to make a mistake and that is with the coils being numbered correctly.

 

The Delco conversion is a plug and play installation, so the terminals must be in the same order out of necessity, however the wire routing will need to be juggled around a bit since all terminals are on one side of the coils.

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I'll check the plug wires themselves (I had labeled them according to the coil numbers), but when I install the Delco unit, I'll set it up how it should be. It had always ran on all cylinders, though.

 

Edit: After looking at pictures of the Magnavox-style ICM, it seems there's spades that get hooked up to the coils and then sandwiched between the two, so I suppose it's possible it was wired correctly, and simply installed upside down. I could take a look at it later, but this seems like the most likely cause.

Edited by TPIGroove
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Not directly related but important to the coil orientation. I was curious if polarity matters in the wiring connections to the coils and it does not. A bit of a surprise, but the coils do not connect to ground through the mounting to the ICM at all. The blue wire is a constant 12v and the striped wires are the trigger/ground connection to the ICM. The coil(s) essentially float relative to ground and the mounting screws are not part of the circuit. Electrically the primary coils can be energized with current flow in either direction so the coils could sit sideways and still work although that would not look very tidy. The secondary winding for each coil is grounded at the two spark plugs, one at either end of the coil so that winding floats independent of the ICM also. It makes my head hurt imagining if the spark itself has polarity or not. I think it does but I am not versed enough in electronic theory to know, and I guess it doesn't matter for this question.

 

Edit: this is for the Magnavox and although operationally similar, polarity may matter on the Delco, but the coils plug in so they only fit one way.

Edited by 2seater
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GM ignition uses a "waste fire"  first seen in early Hondas. In other words the ignition fires two coils at once, twice as often as needed. Both (e.g. 3-6) are at TDC at the same time. They must be in the right order. The Magnavox and Delco are plug and play replacable. See here.

 

BTW the secondary (high voltage) grounds though the spark plug.

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1 hour ago, Padgett said:

GM ignition uses a "waste fire"  first seen in early Hondas. In other words the ignition fires two coils at once, twice as often as needed. Both (e.g. 3-6) are at TDC at the same time. They must be in the right order. The Magnavox and Delco are plug and play replacable. See here.

 

BTW the secondary (high voltage) grounds though the spark plug.

Thanks. I understand the basic concept, and have read various descriptions of how it works. I have seen the comment that only low voltage is required on the cylinder on the exhaust cycle, the waste portion, but if plugs are ground, I would think polarity for both would be one way only. The head scratcher part and I have puzzled about it for years, is this: I have a 4.0L Ford Ranger from the 90's also, with a virtually identical ignition system. Many years ago I replaced the spark plugs and they were mismatched from one side of the engine to the other. I had this vehicle from new, so I was sure they were original. The odd part was they were single platinum plugs, but one side of the engine the platinum was on the center and the side was on the ground strap. Must have been a slight money saver for the OEM and the recommended replacement was double platinum. That would seem to indicate the plugs fire with opposite polarity on one side of the coil vs the other. In my simple electrical understanding, electron flow is from negative to positive, so how can it seemingly be both, or does it rebound somehow with the leftover or waste energy?

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Since I came on the forums back in 2007 I've always heard that the ICM grounds through the baseplate and that it needed to be cleaned each time the ICM was replaced. That might have been because the base plate works as a heat sink to keep it cool in order to avoid the gray goo from melting and running out. Sometimes stories get mixed up over the years. Or maybe I got mixed up over the years. 🙂  Good news is it won't hurt to clean the base plate before installing the ICM.

 

I don't think it would hurt anything for the coil pack to be turned 180 degrees as long as the the wires in the inside are connected properly and the spark plug wires are connected in the proper order.

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45 minutes ago, Ronnie said:

Since I came on the forums back in 2007 I've always heard that the ICM grounds through the baseplate and that it needed to be cleaned each time the ICM was replaced. That might have been because the base plate works as a heat sink to keep it cool in order to avoid the gray goo from melting and running out. Sometimes stories get mixed up over the years. Or maybe I got mixed up over the years. 🙂  Good news is it won't hurt to clean the base plate before installing the ICM.

 

I don't think it would hurt anything for the coil pack to be turned 180 degrees as long as the the wires in the inside are connected properly and the spark plug wires are connected in the proper order.

You are absolutely right, the ICM needs the ground but I have often questioned if the big cast mounting bracket added or removed heat from the ICM🙃 What I was ruminating about was the coilpack itself, which does not have a grounding requirement in the electrical sense, and maybe I have muddied the water. Not my intention. The ICM has several functions in addition to initiating spark, but the coil(s) have a single purpose, and it does not care which direction it is oriented as long as the connections are in the proper order.

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Correct, you have primary ignition (low voltage, cam sensor, crank sensor, ecm, ICM, primary coils) and secondary (high voltage, secondary coils, plug wires, plugs}. First ran into it on a Honda Dream.

Don't forget, at GM if you could save a penny you were a hero (though with a few exceptions,if the execs didn't understant it, the axe came out.

( while at GMI there was a copper shortage, I developed a way to use diode steering (no computers then) and have a single wire front to back (chassis ground) for all of the rear lights . Worked fine but the designated hero couldn't figure it out so nixed for warranty and safety reasons, then the shortage went away)

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Alright, finally managed to crawl just above the freezing point today. The bracket I picked up was correct, but had absolutely no hardware, and the holes the coil screws go into were untapped, so I found some hardware that would work (stainless flat heads just barely worked) and tapped it with a metric tap at work. Went in and checked the plugs against the proper firing order. I'm more than a little confused how this weird mixup happened, but I labeled the plugs with the correct coil numbers. Threw on the Delco ICM and coils, trimmed the three coil screws closest to the engine because there was no hole on the engine mount for them, and she fired right up. The junkyard parts are good, at least. Went for a drive through town.... And the problem's still there. She sounds growly at around 1700 RPM and up still. I don't think it's a hole in the exhaust, because I should hear that even when idling. I'm gonna stop by my mechanic, at the very least he might be able to spot something under the hood (no helpers to rev the engine for me sadly, and I don't want to grab a brick).

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I admire your perseverance, winter mechanic work can be daunting. So this is a sound issue and the performance of the engine is okay? It makes this noise no matter if sitting still in park or on the road and under load? I have had heat shields and other sheet metal stuff vibrate but usually only in a narrow rpm band. A helper would certainly help look, pinpoint, maybe use a stethoscope on various areas while running. I think there are some sound and vibration phone apps available to maybe help nail down a frequency for the sound. 

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I'm hoping it's just something very loose, it only occurs at mid-high RPMs and under load. It's hard to say if there's really a power loss, I don't like gunning it around with a mystery issue in the engine to find out. Idle is still totally normal, though, and if I coast at higher RPMs there's no sound.

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I had to go back and reread this thread. I thought there was a comment that it could be heard, occasionally when free revving it, but as of now, it is only under some load. One way to see if the engine is hearing knock, or some other noise that might retard timing, drive the car in diagnostic mode and watch ED17, Knock counts. It is normal for some knock counts to register just from startup noise, so don't worry about the number that may appear there, this is normal. The thing to look for; is the number increasing during normal driving, specifically when you hear the sound, or the engine seems to struggle. Has the fuel pressure and delivery been verified? I know we headed off in the direction of ignition, but I believe you mechanic questioned fuel delivery way back in the beginning. 

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Maybe the transmission shift modulator keeping the tranny in the wrong gear, lugging the engine?

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Mentioned 1700 rpm. My 88 with Delco ignition goes into OD/lockup at light throttle at 1250 rpm/45 mph and is smooth

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  • 2 weeks later...

Okay, sorry for the radio silence.

 

Dropped it off at the mechanic last tuesday. His shop is mainly a restoration shop and does very good work, so I trust his judgement (plus, I've had plenty of other issues taken care of with him in the past). He confirmed that the car is running pig rich and then checked the ECM. When he did, the ECM sent EVERY single error code it had. He then checked and confirmed the MAF, fuel delivery, and everything else was still in fine working order. He then checked the pinouts to the ECM to make sure there was good continuity, and there was. The only thing he wants to double check are the grounds, but in the meantime he's trying to fine a new ECM and can't seem to locate one.

 

Normally I wouldn't like to point to something like that being the issue, but he's spent a week absolutely making sure it's nothing else. Any ideas on the cause, and worse comes to worst, any good source for new modules? He mentioned the car has 2 EPROMS, and the ECM he received was incorrect and didn't have slots for both.

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6 minutes ago, TPIGroove said:

checked the ECM. When he did, the ECM sent EVERY single error code it had.

I don't doubt he is a good mechanic, but are you sure he is accessing the codes correctly? Sometimes people not familiar with the Buick Reatta get confused on how to check codes. 

 

Read this and you might want him to read it as well unless you sure he is checking codes correctly CRT diagnostics telling me I have problems?

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11 minutes ago, TPIGroove said:

 

 

Normally I wouldn't like to point to something like that being the issue, but he's spent a week absolutely making sure it's nothing else. Any ideas on the cause, and worse comes to worst, any good source for new modules? He mentioned the car has 2 EPROMS, and the ECM he received was incorrect and didn't have slots for both.

He is not looking at the ECM if it has multiple Proms. There are a couple of part numbers for the ECM but it was only used up until 1990 so it will be unlikely to be new ones available. All I ever find are remanufactured ones, Delco, Cardone and others. It should be readily available or Rock Auto or even Amazon has them

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For reference, the ECM stands up vertically in front of the glovebox, there are three large plugs on the bottom, one orange and two black. If he was checking wiring to what he thought was the ECM, I don't know how it could have checked out??

Perhaps he did receive the correct part but was unaware of where it was located?

Edited by 2seater
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The BCM has multiple PROMs, one UVPROM and one EEPROM and is behind the glovebox. The ECM is more by the passenger kick panel and has one UVPROM. TunerCat has lotsa information.

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